The handling of material, including the collection, transport and deposit of the same, is of great concern to virtually all industrialized cultures. Surface transport of materials is largely accomplished by trucking, shipping and rail systems. Particular problems confront the underground mining industry, though, regardless of whether the industry concerns the mining of coal, hard rock mining (for metal bearing ores or other minerals) or for other substances. Problems peculiar to this industry include the narrow confines of an underground mine, the length of time necessary to load a container of material and the substantial weight of most mineral bearing ores.
In the early days of underground mining, material was cut from the underground strata and conveyed to the surface by human porter or by pack animals. In some instances, mechanical advantage was gained by rope and pulley systems which were used to draw wheeled carts or buckets of material to the surface of the mine. Later, with the advent of rail technology, underground mines were often provided with specially constructed railway track systems onto which ore cars could travel with motive power being provided by draft animals, by engines or by electrical motor devices.
These earlier systems, while each normally representing an advancement over its predecessor systems, nonetheless had obvious disadvantages. On the one hand, manual or animal driven systems were labor intensive and were inefficient in removing large quantities of ore from the underground mining operation. On the other hand, rail systems typically required the construction of many miles of track between collection sites and deposit sites, which was quite expensive, or required extra unloading and loading operations. In any event, the track systems further reduced the working area in the narrow confines of a mine since the track systems required a dedicated surface area for installation.
In an effort to further improve material handling systems, some mines utilize special ore carrying vehicles which may be parked at a collection site and, after being filled with the mined material, may be driven to a deposit site, such as a processing plant or materials storage site where a inventory of ore may be collected. The disadvantage of this system resides in the fact that, while being filled with material at the collection site, the transport vehicle is out of service. Where independent tractor/trailer vehicles are employed, the coupling and decoupling of the tractor/trailer vehicles is time consuming and usually requires several worker at a time. Such equipment, by its very nature, is capital intensive.
Accordingly, it is more desirable to employ a plurality of ore receptacles or containers for each combination tractor/trailer vehicle with these containers being simplified housing structures as opposed to complete wheeled trailer vehicles. In such a system, a single tractor vehicle may be used to distribute various containers throughout an underground mining operation and, as each container is filled, the tractor vehicle may retrieve the container, transport the container to a deposit site, dump the material from the container and return it once again to the collection site. A single tractor vehicle thus service a number of containers and collection sites in an efficient manner. This type of system is not without its own problems. In order to accommodate any reasonable period of mining at the collection site, the ore containers must be of sufficient size to hold a substantial volume of mined ore. This creates two problems. First, an increase in size of the container normally makes it more difficult for the tractor and container to maneuver in the narrow confines of the mine. Second, since most ore bearing materials are extremely heavy, any container of suitable volume, when full, is extremely heavy. As a result, the loading apparatus used to move a container from a collection site onto the tractot/trailer vehicle and to thereafter dump the material from the container has heretofore been relatively elaborate which increases the capital expense of the equipment as well as increasing cost due to maintenance costs and lost time due to break downs. Accordingly, there remains a need for improved material handling apparatus which is simplified in construction, which can haul heavy loads and which is highly maneuverable in confined spaces.